Fried my clutch after 2 hrs of riding on a brand new bike.

[Ew83]

Ok not brand new but 5 hours so basically brand new. 2018 yz450f.

In Alaska at trapper creek today. First time ever on a snow bike (or any snow machine) and having a blast. Temps kept right around 180- 183 deg F. But when I would stop they would shoot up to 210. Blankets on both sides and a skid plate. At one point the engine sounds like it's overreving and power isn't going to the track. So I turn it off and adjust the clutch cable and start heading back. Long story short I burnt through a brand new clutch in 2 hours ride time. My KTM 300 has almost 500 hours on it with the original clutch. This yz has a thermobob too. What the heck did I do wrong?? I kept checking temps and while riding with airflow right around 182 deg F. Thought it was going fine until that happened.

So now I gotta pull it apart and replace the clutch. Wish me luck. Will post pics. Also will pull spark plug to check color.

What happened?

 

[Ew83]

Oof. I cringed as I was peeling this off the clutch cover. Need a new blanket now too. I had the zip ties for the blanket on too tight I think as well.

 

[Sheetmetalfab]

Oof. I cringed as I was peeling this off the clutch cover. Need a new blanket now too. I had the zip ties for the blanket on too tight I think as well.


View attachment 364619

Were you clutching for every shift?

maybe partially slipping?

that got really hot.

friction modifiers in the oil?

 

[wwillf01]

Stupid question since its not hydraulic you adjusted freeplay after a bit now hard riding with the cable. And its the stock manual clutch?

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[dooman92]

Ew83, most likely it was slipping. oil temps elevate when clucth slipping. i have both oil and coolant temp gauges. with any snow dust oil temps never see 200, sometimes less than 100 and the coolant temp in both could be 190. when riding trail i have seen 250 plus oil temps with 190 coolant temps. so with the covers etc and no snow dust oil temps get warm. just a thought.

 

[CATSLEDMAN1]

200 degree engine temps won't affect your clutch. 240 won't either. You started with a slipping clutch and finished it. When we first started riding KTM as snowbikes we realized the clutch was slipping and had to go to the stiffer clutch washers, big help.

I have had 3 yamaha snow bikes, never an issue with clutch slipping when properly adjusted.

 

[Revv Up]

I almost hate to ask but.... what oil were you running?

 

[wwillf01]

200 degree engine temps won't affect your clutch. 240 won't either. You started with a slipping clutch and finished it. When we first started riding KTM as snowbikes we realized the clutch was slipping and had to go to the stiffer clutch washers, big help.

I have had 3 yamaha snow bikes, never an issue with clutch slipping when properly adjusted.

Same here with ktm and yamaha .. gets a little more complicated with a rekluse ...

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[Ew83]

Were you clutching for every shift?

maybe partially slipping?

that got really hot.

friction modifiers in the oil?

I didn't clutch much at all.

Probably partially slipping. I'm use to ktm hydro clutch so I probably didn't adjust the cable clutch correctly even though it felt fine.

No friction modifier, the guy who had the bike before me put new oil in before I bought it so I guess I'm not totally sure but almost positive nothing was added to oil.

 

[Ew83]

Stupid question since its not hydraulic you adjusted freeplay after a bit now hard riding with the cable. And its the stock manual clutch?

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Stock manual clutch.

 

[Ew83]

Ew83, most likely it was slipping. oil temps elevate when clucth slipping. i have both oil and coolant temp gauges. with any snow dust oil temps never see 200, sometimes less than 100 and the coolant temp in both could be 190. when riding trail i have seen 250 plus oil temps with 190 coolant temps. so with the covers etc and no snow dust oil temps get warm. just a thought.

I'm coming to this conclusion myself.

 

[Ew83]

200 degree engine temps won't affect your clutch. 240 won't either. You started with a slipping clutch and finished it. When we first started riding KTM as snowbikes we realized the clutch was slipping and had to go to the stiffer clutch washers, big help.

I have had 3 yamaha snow bikes, never an issue with clutch slipping when properly adjusted.

I think you're right. Any advice for the Yamaha? Get clutch spring washers maybe??

 

[Ew83]

Not pretty. Smells like burnt oil. Damn it. Gonna put in new oil filter and clean oil strainer. Also gonna try the timbersled specific oil.

 

[Ew83]

Couple thoughts...

What the heck is the spec for track tension? Could my track be too tight?

Short tangent/tirade: the timbersled support sucks and their install guide sucks. Their install guide gives no spec for track tension, chain case tension, half of the torque values, or how to maintain the track system.

Anyhow, I'm thinking the track might be too tight but I have no idea because I can't find that spec anywhere.

Also what about running stiffer clutch springs, or adding washers to the springs? The clutch springs are still in spec but in between the high and low end of the spec. To get the clutch to not slip, maybe I can run some stiffer springs. Are there any for the Yamaha?

I kinda want to cut a hole in the engine blanket around the clutch cover now.

 

[tribalbc]

Couple thoughts...

What the heck is the spec for track tension? Could my track be too tight?

Short tangent/tirade: the timbersled support sucks and their install guide sucks. Their install guide gives no spec for track tension, chain case tension, half of the torque values, or how to maintain the track system.

Anyhow, I'm thinking the track might be too tight but I have no idea because I can't find that spec anywhere.

Also what about running stiffer clutch springs, or adding washers to the springs? The clutch springs are still in spec but in between the high and low end of the spec. To get the clutch to not slip, maybe I can run some stiffer springs. Are there any for the Yamaha?

I kinda want to cut a hole in the engine blanket around the clutch cover now.

If I were you I would start with replacing the friction plates. Those are cooked now. Clean up your steels and put stiffer springs in or add washers if stiffer springs are not available.

 

[tribalbc]

Make sure your steels aren't warped as well

 

[wwillf01]

I would be replacing steels and plates... those are done done done...

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[wwillf01]

You should be able to roll the kit around without a ton of effort.. 2 to 3 fingers when hanging in the middle of the rails.. I keep mine as loose as possible without ratcheting.. everything is straight tunnel wise and bearings are good? My clutches last 2 to 3 times as long as dirt on a snowbike... I get at least 100 hours... now the question is were the plates toast when you got the bike and he just changed the oil.

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[00Tundra]

 

[eric82930]

So was your clutch cable tight and then you loosened it? If so by then the damage was probably done. Just put in a new clutch and make sure the cable stays loose. If you aren't riding at sea level there is no way the engine is magically making more power than the factory springs can handle and even with friction modifiers it's hard to get them to slip at high altitude because there is way less power than the clutch was engineered to handle.